T value graphs of two independent samples t-test for brain FC between two groups. (A) With the right middle frontal gyrus as the ROI, the FC between the ROI and right insula (peak MNI coordinates: x=38, y=11, z=1) was found to be significantly decreased in the PD + CCPS group. (B) With the left insula as the ROI, the FC between the ROI and bilateral SMA (peak MNI coordinates: left: x=-1, y=-8, z=69; right: x=7, y=-6, z=70) decreased significantly in the PD + CCPS group. (C) With the right insula as the ROI, the FC between the ROI and left middle frontal gyrus (peak MNI coordinates: x=-30, y=40, z=25) decreased significantly in the PD + CCPS group. Color bar indicates the significance levels in the clusters in t values. (p<0.05, TFCE corrected) FC: functional connectivity; ROI: region of interest; SMA: supplementary motor area; MNI: Montreal Neurological Institute.